Question
Physics Question on Combination of capacitors
Two capacitors of 3μF and 6μF are connected in series and a potential difference of 900 V is applied across the combination. They are then disconnected and reconnected in parallel. The potential difference across the combination is
A
Zero
B
100 V
C
200 V
D
400 V
Answer
400 V
Explanation
Solution
Q=CV, Here Q is a constant ∴C∝V1 ∴C2C1=V1V2 ⇒63=V1V2 ⇒V1=2V2 Also V1+V2=900V ∴2V2+V2=900V V2=300V and V1=600V Common potential V=C1+C2C1V1+C2V2 =3×10−6+6×10−63×10−6×600+6×10−6×300 =9×10−61800+1800×10−6=93600 =400V